Essential Hypertension- Primary Prevention - medIND

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Essential Hypertension- Primary Prevention JS Sandhu*, A Berri**, D Gupta**, M Arya**, R Singh**, P Sandhu***,

Introduction Hypertension is the most common disorder encountered in outdoor patients1. The seventh report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC-VII report) has recommended a new classification for adults – 18 years or older 2. 

Normal:

< 120/80 mm Hg.



Pre-hypertension:

120-139/80-90 mm Hg.



Hypertension – stage 1:

140-159/90-99 mm Hg.



Hypertension – stage 2:

≥160/≥100 mm Hg.

As estimated in the Framingham Heart Study3, the residual lifetime risk of incident hypertension (≥140/90 mm Hg) was 90% for both 55 and 65-year-old subjects and lifetime probability of receiving antihypertensives was 60%. In a meta-analysis of 34 epidemiological studies from rural and urban populations of India, it was concluded that hypertension is emerging as a major health problem in India and is more in urban than in rural subjects. The prevalence of hypertension in recent studies was almost similar to those in USA4. In view of high prevalence and very high residual lifetime risk of hypertension in the population and a significant associated morbidity and mortality, especially the cardiovascular and renal, primary prevention of hypertension remains very important. Two strategies have been recommended for the prevention of essential hypertension. These include a population-based strategy and an intensive targeted strategy directed at those with increased risk of developing hypertension5. A. Population based strategy Because most persons in the general population are candidates for primary prevention intervention, a small change in blood pressure is likely to yield

substantial health benefits. A 17% reduction in the prevalence of hypertension, a 14% decrease in the risk of stroke and transient ischemic attacks (TIA), and a 6% reduction in the risk of coronary artery disease occurs by a 2 mm reduction in the population average of diastolic blood pressure (Framingham Heart Study)6. Various population-based strategies for primary prevention of essential hypertension include decreasing sodium content in diet, decreasing caloric density in processed food, and providing safe and convenient opportunities for exercise2. B. Intensive targeted strategy for high risk groups High risk groups of hypertension include: individuals with a high normal blood pressure; a family history of hypertension; African American ancestry; overweight; excess consumption of salt; physical inactivity; and excessive alcohol consumption5.

Lifestyle modifications Lifestyle modifications should be encouraged whenever appropriate. These are generally beneficial in reducing blood pressure and other risks especially cardiac and these should be tailored to the individual characteristics7. A reasonable generalised approach includes: (1) weight loss for the overweight; (2) regular physical activity; (3) moderation in alcohol consumption; (4) dietary modifications to reduce sodium and fat, and increase in calcium, potassium, magnesium, vitamins, and fibre in food sources. 1. Weight reduction Epidemiological studies have revealed a strong relation between obesity and hypertension8. Obesity alone possibly accounts for 78% and 65% of essential hypertension in men and women as revealed in the Framingham study9.

* Professor, ** Resident, Department of Nephrology, *** Associate Professor, Department of Radiology, Dayanand Medical College and Hospital, Ludhiana-141 001, Punjab (India).

Weight loss counselling is an effective approach for the prevention of hypertension. The incidence of obesity has increased to 30.5% in USA and there is a pandemic of obesity worldwide10. Several large epidemiological and clinical studies of weight reduction have explored the role of obesity in the aetiology of hypertension and the effect of weight loss on blood pressure (a 51% and 77% decrease in the incidence of hypertension at 18 months and 7 year follow-up respectively)5.

The regular aerobic physical activity, like brisk walking, swimming, cycling, or treadmill, for at least 30 minutes daily for most days of week is recommended for primary prevention of essential hypertension. However, isometric exercise such as heavy weight lifting can have a pressor effect and should be avoided5. 3. Moderation in alcohol consumption Alcohol consumption elevates blood pressure both acutely and chronically. In cross-sectional and prospective studies involving all kinds of populations, the relationship between alcohol consumption, blood pressure levels, and the prevalence of hypertension has been remarkably consistent5. The relationship is linear. Alcohol consumption ≥ 210 Grams of alcohol/ week (approximately 3 drinks/day) was shown to be associated with an increased risk of hypertension14. The effect increases with age, is independent of the type of alcoholic beverage, and is additive but independent of the effects of obesity, oral contraceptives, and high salt intake. It is estimated that in men, the contribution of alcohol to the prevalence of hypertension is 11%15.

Excess of body fat predisposes to raised blood pressure and hypertension. Weight reduction reduces blood pressure in overweight individuals and has beneficial effects on associated risk factors. The blood pressure lowering effect of weight reduction may be enhanced by a simultaneous increase in physical exercise and alcohol moderation in overweight drinkers and by reduction in sodium intake11. A meta-analysis of randomised controlled trials of weight reduction in normotensive ≥ 45 years old individuals showed a net reduction of 2.8 mm and 2.3 mm Hg in systolic and diastolic blood pressure respectively at 6 months of follow-up12. Based on the overwhelming evidence from clinical trials and metaanalysis, weight reduction is recommended as an important intervention for primary prevention of hypertension. Because sustained weight reduction is so difficult to achieve, more emphasis should be placed on prevention of weight gain, particularly in the young individuals with a high normal blood pressure and in families with a high prevalence of hypertension.

A meta-analysis of randomised trials to assess the effects of alcohol reduction on blood pressure showed a dose dependant decline in blood pressure16. Clinical studies show that blood pressure falls 4 to 5 mm Hg in days or weeks with abstinence from alcohol. For unrelated health reasons, alcohol consumption is not recommended for non-drinkers. However, those who drink alcohol should be advised to limit their consumption to no more than 20-30 g ethanol/day for men and no more than 10-20 g ethanol/day for women11. Thus, reduction in alcohol consumption, especially among heavy drinkers, has been recommended as an important mean of primary prevention of hypertension.

2. Physical activity Physical inactivity has been related to high blood pressure. Aerobic exercise trial meta-analysis in normotensive persons has shown a 4.04- mm and 2.33 mm Hg decrease in systolic and diastolic blood pressure respectively13. Additional benefits of regular physical activity include weight loss, enhanced sense of well being, improved functional health status, and reduced risk of cardiovascular disease and mortality from all causes.

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4. Dietary modification

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The dietary approaches to stop hypertension (DASH) trial17 showed reduction in blood pressure of 3.5/2.1 mm Hg in normotensive individuals on fruit/vegetarian diet combined with reduced fat and cholesterol intake.



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The various dietary modifications recommended for primary prevention are described hereunder.

pressure in both normotensive and hypertensive individuals23. The effect seems to be due to high fibre and low fat content of vegetarian diet as compared to non-vegetarian diet.

a. Dietary sodium reduction Various randomised controlled clinical trials, observational studies across and within population, migration studies and animal experimental data, over the last several decades have shown convincingly causal relationship between dietary salt intake and elevated blood pressure18. In a meta-analysis of 12 randomised controlled clinical trials in 1,689 normotensive individuals, an average reduction of 77 mmol/day in dietary sodium intake resulted in 1.9 mm Hg decrement in systolic blood pressure19. Based on the results of DASH trial and other studies, the National High Blood Pressure Education Programme Coordinating Committee has recommended reduction of dietary sodium intake to not more than 100 mmol/ day (2.4 gm. sodium or 6.0 gm. salt). Even lower levels of dietary sodium intake (< 70 mmol/day) may result in a greater reduction in blood pressure17.

Increased calcium24 and fish oil25 and reduced caffeine consumption26 have shown small blood pressure lowering effects. Observational studies have shown a strong relationship between dietary protein and fibre intake and blood pressure, but clinical trials are scanty27. 5. Stress reduction and biofeedback The role of stress in causing hypertension is still not very clear. However, there is evidence of a link between job stress to long term blood pressure elevation. A meta-analysis of 26 studies of blood pressure control through behavioural or cognitive modifications by techniques such as stress reduction, progressive relaxation, and biofeedback or meditation did not show any superiority to no therapy at all28, 29. 6. Yoga, meditation (Mind-body techniques) These are widely practiced for stress reduction. So far no substantial evidence in support of benefits of yoga/meditation is available. Yet, the availability of some controlled research, its overall costeffectiveness, and the lack of side effects make further investigations of yoga a topmost priority29.

b. Potassium supplementation Over the last several decades, meta-analysis of epidemiological and clinical studies have shown that potassium supplementation lowers blood pressure in normotensive and hypertensive individuals20,21. The blood pressure effect of potassium administration seems to be greater in those who take high salt diet. Based on the data, it is recommended that adequate intake of potassium (> 90 mmol or 3500 mg daily) be taken. The diets rich in potassium include fruits, fruit juices, and vegetables. c.

Macronutrient alteration Based on the results of DASH trial and other studies, a diet rich in fruits, vegetables, and reduced in saturated and total fats is recommended for primary prevention of hypertension. Only 30% of calories should be from fats, with only 7% to 10% of calories from saturated fats. Saturated fats are found in meats, cheese, butter, poultry, and snack foods4, 22. Vegetarian diets have shown reduction in blood

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Conclusion Thus, the main thrust of primary prevention of hypertension includes a sustained effort on lifestyle changes. These include: weight reduction in the overweight; increased physical activity; consumption of a diet that is rich in fruits and vegetables, and low in dairy fat and sodium; and avoidance of excessive alcohol consumption. This would go a long way to prevent the occurrence of hypertension in the general population and decrease the load of chronic diseases (cardiovascular, cerebrovascular, and renal) that are associated with hypertension.

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Chobanian AV, Bakris GL, Blask HR et al. The Seventh Report of the Joint Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure. The JNC7 report. JAMA 2003; 289: 2560-72.

1997; 12: 202-7. 19. Cutler JA, Follman D, Allender PS. Randomised trials of sodium reduction: an overview. Am J Clin Nutr 1997; 65 (suppl 2): 643s-51s.

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Vasan RS, Beiser A, Sheshadri S et al. Residual lifetime risk for developing hypertension in middle-aged women and men: the Framingham Heart Study. JAMA 2002; 287: 100310.

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Gupta R. Meta-analysis of prevalence of hypertension in India. Indian Heart J 1997; 49: 43-8.

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Krousel-Wood MA, Muntner P, He J, Whelton PK. Primary prevention of essential hypertension. Med Clin N Am 2004; 88: 223-38.

22. Appel LJ, Moore TJ, Obarzaknek E et al. A clinical trial of the effects of dietary patterns on blood pressure. DASH Collaborative Research Group. N Engl J Med 1997; 336: 111724.

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Cook NR, Cohen J, Hebert PR et al. Implications of small reductions in diastolic blood pressure in primary prevention. Arch Intern Med 1995; 155: 701-9.

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Guidelines committee. 2003 European Society of Hypertension- European Society of Cardiology guidelines for the management of arterial hypertension. J Hypertension 2003; 21: 1011-53.

24. Bucher HC, Cook RJ, Gyatt GH et al. Effects of dietary calcium supplementation on blood pressure: a meta-analysis of randomised controlled trials. JAMA 1996; 275: 1016-22.

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Bray GA. Risks of obesity. Endocrinol Metab Clin N Am 2003; 32:787-804.

25. Morris MC, Sacks F, Rosner B. Does fish oil lower blood pressure? A meta-analysis of controlled clinical trials. Circulation 1993; 88: 553-33.

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Vasan RS, Larson MG, Leip EP et al. Assessment of frequency of progression to hypertension in non-hypertensive participants in the Framingham Heart Study: a cohort study. Lancet 2001; 358: 1682-6.

26. Jee SH, He J, Whelton PK et al. The effect of chronic coffee drinking on blood pressure: a meta-analysis of controlled clinical trials. Hypertension 1999; 33: 1647-55.

10. Flegal KM, Carroll MD, Ogden CL, Johnson CL. Prevalence and trends in obesity among US adults, 1999-2000. JAMA 2002; 288: 1723-7. 11. Puddey IB, Beilin LJ, Vandongen R, Masarei JR. Effects of alcohol and caloric restriction on blood pressure and serum lipids in overweight men. Hypertension 1992; 20: 533-41. 12. Ebrahim S, Smith GD. Lowering blood pressure: a systematic review of sustained effects of non-pharmacological interventions. J Public Health Med 1998; 20: 441-8.

20. Whelton PK, He J, Cutler JA et al. Effects of oral potassium on blood pressure: meta-analysis of randomised, controlled clinical trials. JAMA 1997; 277: 1624-32. 21. Whelton PK, He J. Potassium in preventing and treating high blood pressure. Semin Nephrol 1999; 19: 494-9.

27. Obarzanek E, Velletri PA, Cutler JA. Dietary protein and blood pressure. JAMA 1996; 275: 1598-603. 28. Eisenberg DM, Delbanco TL, Berkey CS et al. Cognitive behavioral techniques for hypertension: are they effective? Ann Intern Med 1993; 118: 964-72. 29. Sainani GS. Non-drug therapy in prevention and control of hypertension. J Assoc Physicians India 2003; 51: 1001-06.

13. Whelton SP, Chin A, Xin X, He J. Effect of aerobic exercise on blood pressure: a met-analysis of randomised, controlled trials. Ann Intern Med 2002; 136: 493-503. 14. Fucks FD, Chambless LE, Whelton PK et al. Alcohol consumption and the incidence of hypertension: the Atherosclerosis Risk in Communities Study. Hypertension 2001; 37: 1242-50. 15. MacMahon S. Alcohol consumption and hypertension. Hypertension 1987; 9: 111-21. 16. Xin X, He J, Frontini MG, Ogden LG et al. Effects of alcohol reduction on blood pressure: a meta-analysis of randomised, controlled clinical trials. Hypertension 2001; 38: 1112-7. 17. Sacks FM, Svetkey LP, Vollmer WM et al. For the DASHSodium Collaborative Research group. Effects on blood pressure of reduced sodium and the Dietary Approaches to Stop Hypertension (DASH) diet. N Engl J Med 2001; 344: 3-10. 18. He J, Whelton PK. Role of sodium reduction in the treatment and prevention of hypertension [review]. Cirr Opin Cardiol

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ANNOUNCEMENT EMERGENCY MEDICINE UPDATE 2004 30th October, 2004 All India Institute of Medical Sciences Department of Emergency Medicine, AIIMS Last date : 15th October, 2004 For details contact :

Dr. Sanjeev Bhoi, AP (Organising Secretary) Department of Emergency Medicine, AIIMS Ansari Nagar, New Delhi-110 029 (India) Tel. : 91-11-26589029 Mobile : 91-9811044309 E-mail : [email protected]



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